According to the prior art, a polysiloxane is produced by hydrolyzing a chlorosilane. The long chain of a polysiloxane molecule is composed of silicon atoms which alternate with oxygen atoms and is surrounded by organic molecular groups to thereby acquire organic properties and inorganic properties. The most important characteristics of polysiloxanes include their tolerance to high heat, low temperature, adverse circumstances, ozone, and solvents, electrical insulation, hydrophobicity, and permeability. With their glass-rubber transition temperatures (Tg) being extremely low, polysiloxanes exhibit special mechanical properties and electrical performance within a wide range of temperatures; hence, polysiloxanes have wide application in commerce and defense. Since silicones are incompatible with most organic polymers, silicones are widely used as release agents for plastics, rubber, glass, and metals and used as a defoamer, a lubricant, and a polisher.
A modifying process of a polymeric material typically involves introducing a small amount of rubber into a plastic by means of doping or copolymerization. In this regard, polysiloxanes also serve as a modifier for phenolic resin, acrylic resin, and epoxy resin, though the resultant modification is seldom smooth, not only because polysiloxanes are incompatible with the other polymers, but also because the resultant polymerization manifests a wide variety of results.
According to the prior art, a polysiloxane polymer undergoes a cross-linking reaction in the presence of a curing agent to produce a three-dimensional crosslinkable polymer. For instance, an unsaturated bond and a Si—H bond of a polysiloxane react to undergo a polyaddition reaction and thus get cross-linked. Furthermore, a polysiloxane polymer undergoes a cross-linking reaction in the presence of a cross-linking agent which produces free radicals; however, the cross-linking reaction based on two reagents proves disadvantageous in terms of application and properties adjustment. Hence, it is imperative to develop a polysiloxane molecule which not only manifests cross-linking reaction characteristics but also has novelty and non-obviousness.
In this regard, a benzoxazine group effectuates self-polymerization by undergoing a ring opening polyaddition reaction. Hence, if a benzoxazine group reacts with the chain of a polymer, the polymer will become capable of undergoing cross-linking spontaneously. In addition, even when heated up, the benzoxazine does not produce any volatile by-product and thus can undergo curing to thereby exhibit heat tolerance, non-flammability, excellent electrical characteristics, and applicability in electronic-oriented materials, such as laminated boards, adhesives, and packaging agents. Therefore, plenty of molecules for use in integrating a benzoxazine and a siloxane structure are synthesized, and these molecules are mostly polysiloxane molecules each with their two ends carrying a benzoxazine group. The characteristics of the chain of the polysiloxane molecule are conducive to improvement of the properties of benzoxazine polymers. Moreover, it is feasible to synthesize a polymeric chain composed of repetitive units of polysiloxane, and its backbone chain carries a benzoxazine group to overcome an otherwise existing drawback—the polymers become brittle upon completion of a cross-linking reaction. The prior art usually entails using a polysiloxane to improve the benzoxazine group polymers which function conventionally as thermosetting resins rather than developing a polysiloxane which has novel structures and properties and is capable of undergoing a cross-linking reaction.